Bake lamb, uncovered, until very tender, 4 to 4 1/2 hours. Using slotted spoon, transfer lamb to bowl. Tilt baking dish and spoon off fat from surface of sauce. Return lamb to sauce; stir to blend. Season stew to taste with salt and pepper. DO AHEAD Can be made 2 days ahead. Chill stew, uncovered, until cold, then cover and keep refrigerated. Rewarm, covered, in 350°F oven 30 minutes.